The present invention generally relates to user interface systems, and more particularly to a user interface system that generates an image and position of a pointer in response to light from a positionable light source.
Video communication systems have become increasingly popular. Video conferencing, for example, is becoming more common in both business and residential applications. Video conferencing permits audio as well as visual live communication between two remotely located terminals communicating over a single channel.
The apparent convergence of video and computing communication media is illustrated by the VC55 Modular Videophone with Web Browser videophone from 8xc3x978, Inc. As described in the attached appendix, the VC55 includes both video conferencing and web browser capabilities in a single set-top box.
A system having the aforementioned combination of features challenges user-interface designers. The VC55 uses the keypad of a conventional touchtone telephone for a user control interface. While access to certain menu-driven functions is reasonably convenient using a keypad, Web browser control via a keypad is less convenient given the point-and-click nature of the browser user interface. Whereas a mouse may be suitable for PC-based video conferencing applications, the cabled nature of a mouse may be an impediment to convenient operation in applications that are not PC-based. Other approaches to wireless user-interfaces involve recognition of an object, such as a hand or a pen, within an image and tracking the motion of the object. Such approaches can be expensive in terms of sophisticated hardware and software.
The present invention is directed to user interface methods and arrangements for use in controlling computer based applications. In a first aspect of the invention, a method is provided for tracking within frames of digital video data movement of a light source that emits modulated light having a modulation frequency, wherein the modulation frequency of the light is different from a frequency of the frames of digital video data. The method comprises the steps of: determining presence of the light as a function of relative luminances of portions of a frame of digital video data and difference luminances between the portions of the frame and corresponding portions of a previous frame; storing coordinates and associated peak codes for selected portions of the frame, the peak codes indicative of relative luminances and difference luminances of the selected portions, and the selected portions having the greatest relative luminances and difference luminances; determining a position of the light within a frame as a function of the relative luminances, the difference luminances, and coordinates and associated peak codes of the selected portions of the frame relative to coordinates and associated peak codes of selected portions of the previous frame.
In another aspect of the invention, there is an apparatus for tracking within frames of digital video data movement of a modulated light source that emits light having a modulation frequency, wherein the modulation frequency of the light is different from a frequency of the frames of digital video data. The apparatus comprises: means for determining presence of the light as a function of relative luminances of portions of a frame of digital video data and difference luminances between the portions of the frame and corresponding portions of a previous frame; means for storing coordinates and associated peak codes for selected portions of the frame, the peak codes indicative of relative luminances and difference luminances of the selected portions, and the selected portions having the greatest relative luminances and difference luminances; means for determining a position of the light within a frame as a function of the relative luminances, the difference luminances, and coordinates and associated peak codes of the selected portions of the frame relative to coordinates and associated peak codes of selected portions of the previous frame.
A user interface circuit arrangement is another aspect of the invention. The circuit arrangement comprises: a camera configured and arranged to provide digital video images; a first detection circuit coupled to the camera and configured and arranged to detect a presence of modulated light having a first modulation frequency represented in the digital video images and generating a first signal in response to the presence of the modulated light; a tracking circuit coupled to the detection circuit and to the camera and configured and arranged to detect movement of the modulated light represented in the digital video images in response to the first signal from the detection circuit; and a second detection circuit coupled to the first detection circuit and configured and arranged to detect modulated light having a second modulation frequency represented in the digital video images and generating a second signal in response to the presence of the modulated light having the second modulation frequency and the first signal.
The above Summary of the Invention is not intended to describe each disclosed embodiment of the present invention. This is the purpose of the figures and of the Detailed Description that follows.